Abstract In Causing Actions, Pietroski defends a distinctive view of the relationship between mind and body which he calls Personal Dualism. Central to his defence is the Argument from Differential Vagueness. It moves from the claim that mental events have different vagueness of spatiotemporal boundaries from neural events to the claim that mental events are not identical to neural events. In response, I argue that this presupposes an ontological account of vagueness that there is no reason to believe in this context. I further argue that Pietroski's reasons for rejecting the possibility that mental events are vaguely constituted from neural events are inadequate. I go on to show how Pietroski's Personal Dualism is ill-equipped to deal with the problem of mental causation because of its apparently necessary appeal to ceteris paribus laws